Fatigue crack-growth behavior of wrought and additively manufactured 17 - 4 PH stainless steel specimens

Abstract

Additive Manufacturing (AM) technologies potentially offer numerous advantages, first and foremost the reduction of the lead-time of new products and the possibility of producing any kind of complex shape. Selective laser melting (SLM) processes are the most popular processes for AM of metals; currently, several types of stainless steel have been widely processed via SLM as steel provides a broad range of desirable properties like good ductility, high strength, low cost, and recyclability. Therefore, it is largely used in both industrial and domestic products. However, many factors, such as crack orientation, porosities, residual stresses, heat treatments, corrosion, etc., can degrade the performances of SLM materials significantly, if compared to those of the wrought ones. Therefore, in this work the fatigue crack propagation behaviors of wrought and AM 17-4 PH stainless steel were measured experimentally by considering different crack orientations. Tests were carried out using standard compact-tension C(T) specimens tested at R = 0.1 at a frequency of 5 Hz. The main objective was to study the effect of the crack orientation on crack-length vs. number of cycles curves.